Hydraulic drive



`lune 2,y 1942. R. TYLER HYDRAULIC DRIVE Fileduune 23, 1958 ...II I-lmsll al \/\f INVENTOR.

"" HANSUM 'TYLER BY v ATTORNEY.

' Patented June 119.142V a nvnaamc univa Ransom Tyler, Greenfield, Wis.,v assigner to The -Oilgcar Company. Milwaukee, Wis., a corporation of Wisconsin Application June y23, 193%,` Serial No. 215,420

9 Claims. (Cl. 60 53) This invention relates to drives for machines which require to be driven at two different speeds, suchr4 as a rotary printing press which should be driven at a. low speedwhen a web of paper is being threaded therethrough and at 5 a high speed when the paper is being printed by the press. When changing from low speed to high speed, the press should be accelerated gradually to avoid breaking the web of paper, and

it is also desirable that the press be decelerated l gradually. I

The present invention has as an object to provide a drive which will drive a machine at either of two predetermined speeds, which will gradually accelerate the. machine from low speed to l high speed and which will gradually decelerate the machine from high speed to low speed. A

Another object is to provide a drive of this character which is relatively simple in construc tion and susceptible of close adjustment and control.- I l Other objects and advantages will appear from the :description hereinafter given of a drive v in which. the invention is embodied.

According to the invention in its general aspect 4zo and as ordinarily embodied in practice, a hydraulic motor for driving a machine is energized by liquid supplied'thereto from a pump having a member which is shiftablebetween two preset positions to cause the pumpto deliver. liquid at one or the other of two predetermined rates and thereby cause the motor to drive the machine at one or the other of two predetermined speeds, and means are provided for limiting the rate at A which pump delivery is varied to thereby cause the speed of the machine to be gradually varied from one speed to the other.

The invention is exempliiied by the hydraulic drive shown schematically in the accompanying drawing in which the views are as follows: 440

, Fig. 1 is a diagram yof theA hydraulic circuit.

Fig. 2 is a view showing a start and stop valve in a position different from that shown in Fig. 1.

Fig. 3 is a view showing a control valveV in a position different from that shown in Fig. 1.

Since the machine -to be driven forms no part of the present invention, it has beeh represented by a single roller I and shown'as being connected by a `suitable drive 2.to a constant displacement rotary hydraulic lmotor 3. Liquid for energizing motor 3 is supplied thereto by a variable displacement pump 4 which may be of any suitable type.

The pump shown schematically in Fig. 1 is of the rolling piston type which is fully illustrated and describedm Patent No. 2,014,068. n is v deemed suilicient to state herein that pump 4 has its pistons and cylinders arranged radially in a cylinder barrel 5 which rotates upon a sta-- tionary valve shaft or pintle B having formed therein ports and passages through 'which liquid flows to and from the cylinders, that the outer ends of the pistons react against an annular reaction surface'l which inpractice is formed in a separate rotatable thrust member carried by a slide block 8 but which has been shown as b eing formed in slide block 8, that pump 'Il will discharge liquid at a rate dependent upon the dis-j tance the axis of reaction surface 'l is offset to-v ward the right from theaxis 'of cylinder barrel 5, and that slide block 8 is arranged in a casing 9 which permits' it-to be moved transversely of pintle 6 but prevents it from moving in any other direction.

Pump 4 discharges liquid into a supply channel I0 which has one of its ends in communication with the ports and passages in oneslde of pintle 6 and its other end connected to the inlet port of motor 3.r 4Liquid is returned from` motor,

3 to pump 4 ,through a channel II which communicates ywith the ports and passages in the other side of pintle 6.

The delivery of liquid to motor B-is controlled by a startend stop valve I4 which is fitted in a valve casing I5 and urged toward thev left to the position shown in Fig. y1 by a helical compression spring I6 and which is adapted to be moved toward the right to the position shown in Fig. 2 by a solenoid I1 to the core of which the stem of valve Il is connected.

In order to prevent the movement of valve I4 from being hampered by entrapped liquid or gas, the extreme ends of vvalve casing I5 are connected to a drain channel I8 which discharges are formed in the bore `of casing I5. Port 22 -is connected by a channel 26 to supply channel I0 intermediate the ends thereof. Port 23 has the other end of return channel I I connected thereto. Port 24 is connected byV a channel 2l to thedischarge port of motor 3. ,Port 25 is connected by a channel 28 to the inlet o! a resistance valve 29 which functions as a brake and discharges into drain channel i9. l Y

When valve I4 is in the position shown in Fig.

uid through channel I to motor 3 and cause it Y to drive machine I. The liquid-discharged at this time by motor will now through channel 2, valve casing I `and channel il to the intake `of pump 4. The pressure created by pump 4 is limited by arelief valve 30 which is connected bya channel 3| to channel i8 and discharges into reservoir I3.

When valve I4 is in the position shown in Fig.

1, channel I0 is open to channel I I through chan- Y nel 23 and valve casing i5 so that pump 4 is bypassed. The liquid discharged at this time by motor 3 'passes through channel 21, valve casing I5, channel '28, brake valve 29 and drain channel I8 into reservoir I9, brake valve 29 resisting the passage of liquid therethrough and thereby functioning as a brake t'o decelerate motor 3 and Vmachine I.

The liquid discharged by motor 3 vwhen stopping is drawn from channel I4 so that the volume returned to pump 4 throughchannel II is considerably less than the volume required to keep the pump cylinders illled. Consequently, liquid must be supplied to pump 4 from reservoir I9 to make up for the volume, that passes through motor 3.

Pump 4 is supercharged by a gear pump to be presently described but, in case the volume supplied by the gear pump is insufiicient to make up for the volume that passes through motor 3 when arranged in the casing thereof according to the usual practice but which for the purpose of illustration has been shown separate from pump 4 and adapted to draw liquid from reservoir i9 and discharge it into a low pressure supply channel 35.

The pressure created by gear'pump 34 is limited by a relief valve 35 which has its inlet connected to channel 35 and its outlet'connected by 2,284,852 f' .2 and pump 4 is running, pump 4'will deliver liqpredetermined .maximum by two servo-motors one of which is larger than the` other and both of which are operatedby liquid supplied by gear pump 84. As shown, the smaller servo-motor has its piston 4i -connected to slide block 8 andv fitted in a cylinder 42 arranged upon one side of pump casing u, and the larger servo-motor has its piston .43 connected to slide block 8 and fitted in a cylinder 44 arranged upon the other side of pump v casing 8. The movement of slide block 8 is limchannel 35 to cylinder 42 so that slide block 8 is constantly urged toward the` left by the liquid acting upon piston 4I. Check valve 48 prevents liquid from escaping from' cylinder 42 except through an adjustable'choke 49 which is connected in parallel with check valve 48 and regulates the speed at whichslide block 8 may move toward the right.

The flow of liquid to and from cylinder 44 is controlled by a valve 52 which is iitted in a valve casing 53 and urged toward the right to the position shown in Fig. v1 by a helical compression spring 54 arranged between valve 52 'and one end ofcasing 53.- Valve 52 is adaptedv to be moved toward the left to the position shown in Fig. 3 by a 'solenoid 55 which has its core connected to the stem of valve 52. In order to prevent the ports 5l, 58 and 58 formed in the wall of its bore intermediate the endsthereof. Port 51 has supply channel 35 connected thereto. Port 59 is connected to drain channel I8. Port 58 is arranged between ports 51and559 and connected to cylinder 44 by a channel 53, a check valve 5I and a channel 52'.

Check valve 8i permits liquid to ilow freely to cylinder 44 but prevents it from escapingv from cylinder 44 except through an adjustable choke a channel 31 to suction channel 32 above check vvalve 33. The pressure in channel 32 -is limited by a relief valve 38 which discharges into lreservoir I3 and has its inlet connected to suction channel 32 at a point above check valve 33.

Gear pump 34 discharges liquid at a rate in excess of requirements except possibly when motor 3 is discharging through brake valve 28 as explained above. At all other times, the excess liquid discharged by gear pump 34 is enhausted through relief valves 35 and S8 into reservoir I3. Relief valve 35 may be of the ordinary type but it is preferably of the type that is not aiected by back pressure. The arrangement is such that gear pump 34 is able to main- `tain at alltimes in channel 35 a pressure equal to the resistance of relief valve 35 and to maintain in channel 32 a pressure equal tothe resistance of relief valve 38 whenever pump 4 is not drawing liquid through channel 32 from reser- The displacement of pump 4 is adapted to be 63 which has its inlet connected to channel 62 and its outlet connected to channel 60. Choke 53 limits the rate at which liquid may escape from cylinder 44 and thereby limits the rate at which slide block 8 may move toward the left.

Instead of arranging check valves 48 and 5I and chokes 43 and 63 as shown, the positions thereof may be reversed so that the movement of slide block c would be controlled by throwing the ow of liquid to cylinders 42 and 44 and liquid could escape freely therefrom.

Brake lvalve'29 has sufllcient resistance to cause motor 3 and machine I to stop very quickly after valve I4 has been shifted to the position shown in Fig. 1,-and choke 63 causes slide block 8 to move slowly from its maximum/displacement position to its minimum displacement position. Therefore, if the operator should restart the machine immediately after stopping it, slide block 8 varied between a predetermined minimum and a In order to avoid this danger, provision is are connected to drain channel,

made for causing slide block 8 to be moved to its minimum displacement position substantially instantaneously when valve ld is operated to stop the machine.

As showm channel 62 is connected by a channel dt to a port 65 which is Vformed in the bore of valve casing l and controlled by valve 14. 'The arrangement is such that, when valve It is in the position shown in Fig. 2,' port 65 is blocked so that no liquid can escape from-cylinder til through channel di and the movement oi slide block u is controlled by valve 52 but, when valve ld is in the position shown in Fig. 1, port es is open to drain channel la so that liquid-A may escape freely from cylinder it through channels t2 and Bt, valve casing i5 and drain channel it into reservoir lli, thereby permitting piston d! to move slide block u to' its. minimum displacement position substantially linstantaneously.

' Operation v Assuming that ,valves ifi and 52 are in the positions shown in Fig. 1 and that pumps d and 3l are running, the drive will operate as follows:

Pressure from gear pump 3ft will extend to cylinder 42 and cause piston 4| to hold piston t@ against adjusting screw 45 in whlch'position oi slide block 8 pump t will discharge liquid at a predetermined minimumrate as determined by the adjustment of screw 46, and the liquid discharged by pump 4 will flow through channels lo and 26, valve casing l5 and channel il to the intake ci'l pump 4 so that motor 8 will remain idle. 'f

When solenoid Il is energized, it will shift valve it from the position shown in Fig. 1 tothe position shown inl Fig. 2 and then liquid from pump t will fio'w through channel I0 to motor 3 and cause it to drive machine lat a slow speed appropriate for threading a web of paper through a printing press, the' speed being determined Y i by the adjustment of screw 4t.

Then when solenoid |55, is energized, itl will shift valve t2 from the position shown in Fig. 1 to the 'position shown in Fig. 3 vso that port 5 1 is opened to port 58 and pox-tit is blocked. s Liquid .from gear pump 34 may then ow through channel35, valve casing 53, channel 60, check valve 6l and channel 62 to cylinder `44. 'Since v cylinder M is larger than cylinder 42,4 the force .exerted by the liquid upon piston 43 will cause it to move slide block 8 toward the right to increase pump displacement to maximum as determined by the adjustment of screw 4B. Slide block 8 in moving toward the right will cause piston 4l to expel'liquid from cylinder 42 through channel 41 and choke 49 into channel 35.

Choke 49 will limit the rate o f flow therethrough and thereby cause slide block .l to move at a limited rate so that pump displacement and delivery are gradually increased from the predetermined minimum to the predetermined maximum with the'result that motor s is caused to 6i to move slide block B toward the lett to reduce the displacement or pump tto minimum.

Slide block 8 in moving toward' the leit will cause piston 48 to expel liquid 'from cylinder di throughchannel 82, choke t3, channel du, valve Vcause motor t and .machine l to be gradually decelerated from high speed to low speed. When it is desired to stop the machine, solenoid I1 is deenergized and spring it will shift valve It to the position shown in Fig. l, thereby bypassing pump# and causing motor t to dis- 'chargethrough lbrake valve 2Q as previously ex- Shifting valve It to its'Fig. l. position opens would be open to drain through valve casing 53, channel 60, check valve di, channels @i and 54 and valve casing It. Therefore, in order to prevent the loss of gear pump liquid and to enable gear pump 36 to create pressure toeperate servo-motor 4l-42, solenoids it and 5t are deenergized simultaneously by operating a single push button switch 86 arranged in a control panel 61.

` The invention herein set forth is susceptible ofrvarious modifications without departing from the scope thereof as hereafter claimed.

The invention is hereby claimed as follows:

l. A drive for operating a machine at predetermined speeds, comprising 'a hydraulic motor for driving said machine, a pump for supplying liquid to said motor to energize the same, hy-

draulic servo-motor means for varying the volumetric delivery of said pump between two predetermined rates to thereby cause said motor to drive said machine either at a predetermined minimum speed or at a predetermined maximum speed, means for supplying liquid to said servo-motor means to energize the same, means -for controlling the operation of said servomotor means; choke means forlimitlng the rate of operation of said servo-motor means to thereby cause the-delivery of said pump to be gradually varied from one to the otherof said rates. a valve for bypassing liquid around said choke means to thereby enable said servo-motor means tov quickly vary the delivery. of said pump from vone to the other of saidl rates, and means for operating said valve to render said choke means effective or ineffective.

2. A drive for operating a machine at predeterminedspeeds, comprising a hydraulic motor for driving said machine, a pump for supplying liquid `to said motor to energize the same, hydraulic servo-motor means for varying the 'volumetricdelivery of said pump between two predetermined rates to thereby cause said motor to drive saidA machine either at a predetermined Yminimum speed or -at u,Y predetermined mnximumspeed, means for supplying liquid to said servo-motor means to energize the same,` means for controlling the operation of said servo-motor means.' choke means for limiting the rate of operation oi said servo-motor means by gear pump 34 to cylinder 42 can cause piston 75 to thereby cause the delivery of said pump to be gradually varied from one to trie other of said rates, means for short circuiting said pump, and means operated in unison with said short circuiting means for bypassing liquid around said choke means to thereby enable said servo-motor means to quickly vary the delivery of said pump from one to the other of said rates.

3.a drive for operating a machiney at predetermined speeds, comprising a hydraulic motor for driving said machine, a pump for supplying liquid to said motor to energize .the same. luycontrolling the operation of said' servo-motor' means, choke means for limiting the rate of `operation of said servo-motor means to thereby cause the delivery of said pump to be gradually varied from one to the other of said rates, and

a valve for controlling operation of said motorv and for bypassing liquid around said choke means to thereby enable said servo-motor means to quickly vary the delivery of said pump from one to the other of said rates.

4. A drive for operating a machine at predetermined speeds, comprising a hydraulic motor for driving said machine, Aa pump for supplying liquid to said motor to energize the same, hy-' draulic servo-motor means for varying the volumetric delivery of said pump between two predetermined rates to thereby cause said motor to drive said machine either at a predetermined minimum speed or at a predetermined maximum speed, means for supplying liquid to said servo-motor means to energize the same, a valve for controlling the operation of said servo-motor means, choke means for limiting the rate of operation of said servo-motor means to thereby cause the delivery of said pump to be gradually varied from one to the other of said rates, a valve for controlling operation of said motor and for bypassing liquid around said choke means to thereby enable said servo-motor means to quickly vary the delivery of said pump from one to the other of said rates, and means for operating both of said valves simultaneously.

5. A hydraulic drive, comprising a hydraulic motor, a pump hydraulically connected to said motor for supplying liquid thereto to energize the same and having a member for varying its displacement, servo-motor Vmeans for shifting said member between two preset limits to thereby vary pump delivery between two predeterthe same and having a member for varying its displacement, servo-motor means for shitting said member between two preset limits to therel gradually varied from one to the other of said rates, means for short circuiting said pump, and means operable in unison with said short circuiting means for bypassing liquid around said choke means during movement of said member in one direction Vto enable said servo-motor means to shift said member at high speed in said direction and thereby quickly vary pump deliv'- `ery from the higher to the lower of saidrates.

7. A drive for operating a machine at predetermined speeds, comprising a hydraulic motor for driving said machine, a pump for supplying liquid to said motor to energize the'same and having a member shiftable in opposite directions to vary the volumetric delivery of said pump between a predetermined maximum and a predetermined minimum, two hydraulic servo-motors" for shifting said member in one direction or the other to vary the volumetric delivery of said pump between two predetermined rates and thereby cause said motor to drive said machine either at a predetermined minimum speed or at a predetermined maximum speed, means for supplying motive liquid to said servo-motors, means for controlling the operation of said servo-motors, choke means for limiting the rate of operation of said servo-motors so as to gradually change pump delivery from one to the other of.

ing a brake load to said motor, and means co- I acting with the last mentioned means for connecting one of said vservo-motors to drain to thereby enable the other servo-motor to reduce pump displacement to the minimum substantially simultaneously with the application of a brake load to said motor. Y

8. A drive for operating a machine at predetermined speeds, comprising a hydraulic motor for driving said machine, a pump for supplying liquid to said motor to energize the same and having a member shiftable in opposite directions to vary the volumetric delivery of said pump between a predetermined maximum and a predetermined minimum, two hydraulic servo-motors for shifting said member in one direction-or the other to vary the volumetric delivery of said be graduallyvaried from one to the other of vsaid rates, a valve for-bypassing liquid .around said choke means during movement of said member in oneA direction to enable said servomotor means to shift said member at high speed in said direction. and thereby quickly vary pump delivery from the higher to the lower of said rates, and means' for operating said valve to.

rendersaid `choke effective or ineffective.

6. A hydraulic drive, comprising a hydraulic motor, a pump hydraulically connected to 'said pump ybetween two predetermined rates and thereby cause said motor to drive said machine either at a predetermined minimum speed orat a.

other of said predetermined speeds, a brake valve,

and astart and stop valve operable either to direct liquid from said pump to said motor and from said motor to said pump or to bypass said pump motor for supplying uquid thereto te energize and directliquid from said motor to said brake valve, said start and stop valve when shifted to a position to bypass said pump being also adapted to connect one of said servo-'motors to drain to thereby enable the other servo-motor to reduce pump displacement to minimum substantially instantaneously,

9. A drive for operating a` machine at predetermined speeds, comprising a hydraulic motor for driving said machine, a pump for supplying.

liquid to said motor to energize the'same and having a member shiftable in opposite directions to vary the volumetric delivery of said pump between a predetermined minimum and a predetermined maximum, a source o'f constant pressure liquid, a small servo-motor connected to said source and constantly urging said member in a direction toward minimum delivery position, a large servo-motor for moving said member in the opposite direction toward maximum 'delivery position, means including a valve for either con-v motor to said source to enable it to move said member in said opposite direction whereby the delivery of said pump is varied between two predetermined rates and said motor is caused to drive said machine either at a predetermined maximum speed or at 'a predetermined minimum speed, a choke connected to each of said servo` necting said large servo-motor to drain to enable said smallservo-motor .to move said member in said direction or for connecting said large servomotors for limiting the rate at which liquid may escape therefrom to thereby cause said servomotors to gradually vary pump displacement with the resultant gradual variation in the speed 4of said machine, a'brake valve for applying a 

